Method of polishing silicon wafer

Abstract

A silicon wafer is polished by applying a polishing solution substantially containing no abrasive grain onto a surface of a polishing pad having a given fixed grain bonded abrasive and then relatively sliding the polishing pad to a silicon wafer to polish the surface of the silicon wafer, wherein a hydroplane layer is formed by the polishing solution supplied between the surface of the silicon wafer and the surface of the polishing pad and a thickness of the hydroplane layer is controlled to change a polishing state of the surface of the silicon wafer.

What is claimed is: 
     
       1. A method of polishing a surface of a silicon wafer, comprising steps of:
 applying a polishing solution containing substantially no abrasive grain onto a surface of a polishing pad having a fixed grain bonded abrasive; 
 sliding the surface of the polishing pad relative to the surface of the silicon wafer to polish the surface of the silicon wafer; 
 reducing a thickness of a hydroplane layer formed by the polishing solution present between the surface of the silicon wafer and the surface of the polishing pad to a thickness in a range of 10 nm to 1 μm, to remove an oxide film formed on the surface of the silicon wafer; and, 
 after the reducing step, increasing the thickness of the hydroplane layer to a thickness in a range of 5 μm to 10 μm, to perform finish polishing of the surface of the silicon wafer. 
 
     
     
       2. The method of polishing a surface of a silicon wafer according to  claim 1 , wherein the thickness of the hydroplane layer is controlled by a pressure applied to the polishing pad in a vertical direction to the surface of the silicon wafer, a relative sliding speed of the polishing pad and/or a viscosity of the polishing solution. 
     
     
       3. The method of polishing a surface of a silicon wafer according to  claim 2 , wherein the thickness of the hydroplane layer is further controlled by a hardness of the polishing pad and/or a size of a contact area between the fixed grain bonded abrasive of the polishing pad and the surface of the silicon wafer. 
     
     
       4. The method of polishing a surface of a silicon wafer according to  claim 1 , wherein the silicon wafer has a diameter of not less than 450 mm. 
     
     
       5. A method of polishing a surface of a silicon wafer, comprising steps of:
 applying a polishing solution containing substantially no abrasive grain onto a surface of a polishing pad having a fixed grain bonded abrasive; 
 sliding the surface of the polishing pad relative to the surface of the silicon wafer to polish the surface of the silicon wafer; 
 reducing a thickness of a hydroplane layer formed by the polishing solution present between the surface of the silicon wafer and the surface of the polishing pad, to remove an oxide film formed on the surface of the silicon wafer; and 
 increasing the thickness of the hydroplane layer, to perform finish polishing of the surface of the silicon wafer, 
 wherein the thickness of the hydroplane layer is changed in a controlled manner by changing a pressure applied to the polishing pad in a vertical direction to the surface of the silicon wafer, a relative sliding speed of the polishing pad and/or a viscosity of the polishing solution, and a hardness of the polishing pad and/or a size of a contact area between the fixed grain bonded abrasive of the polishing pad and the surface of the silicon wafer. 
 
     
     
       6. A method of polishing a surface of a silicon wafer, comprising steps of:
 applying a polishing solution containing substantially no abrasive grain onto a surface of a polishing pad having a fixed grain bonded abrasive; 
 sliding the surface of the polishing pad relative to the surface of the silicon wafer to polish the surface of the silicon wafer; 
 reducing a thickness of a hydroplane layer formed by the polishing solution present between the surface of the silicon wafer and the surface of the polishing pad in a first polish, to remove an oxide film formed on the surface of the silicon wafer; and, 
 after the reducing step, increasing the thickness of the hydroplane layer in a second polish, to perform finish polishing of the surface of the silicon wafer, 
 wherein the thickness of the hydroplane layer is changed in a controlled manner by one of: changing a pressure applied to the polishing pad in a vertical direction to the surface of the silicon wafer while keeping a relative sliding speed of the polishing pad constant, and keeping the pressure applied to the polishing pad in the vertical direction to the surface of the silicon wafer constant while changing the relative sliding speed of the polishing pad. 
 
     
     
       7. A method of polishing a surface of a silicon wafer according to  claim 6 , wherein the thickness of the hydroplane layer is changed in a controlled manner between the first polish and the second polish by decreasing a pressure applied to the polishing pad in the vertical direction to the surface of the silicon wafer while keeping the relative sliding speed of the polishing pad constant. 
     
     
       8. A method of polishing a surface of a silicon wafer according to  claim 6 , wherein the thickness of the hydroplane layer is changed in a controlled manner between the first polish and the second polish by increasing the relative sliding speed of the polishing pad while keeping the pressure applied to the polishing pad in the vertical direction to the surface of the silicon wafer constant.